Izvestiya vuzov. Yadernaya Energetika

The peer-reviewed scientific and technology journal. ISSN: 0204-3327

Development and Testing of a High-Temperature Treatment Facility Mock-Up for Pyroprocessing of Mixed Uranium-Plutonium Nitride SNF at Reprocessing Module of Experimental and Demonstration Energy Complex

3/27/2026 2026 - #01 Physics and technology of nuclear reactors

Smirnov V.P. Samsonov A.A. Leshchenko A.Yu. Nosov A.V. Mochalov Yu.S. Savchits S.M. Legen’kij A.A.

DOI: https://doi.org/10.26583/npe.2026.1.03

UDC: 621.039.59

The paper presents results of testing a scaled mock-up high-temperature facility for the treatment of mixed uranium-plutonium nitride spent nuclear fuel (SNF) from the BREST-OD-300 reactor. This mock-up is designed to test selected high-temperature treatment (HTT) process parameters on model nuclear fuel (MNF) and allows design development testing of pyroprocessing equipment for fast neutron reactor SNF at the Reprocessing Module of the Experimental and Demonstration Energy Complex. The performance of the mock-up facility was preliminarily evaluated using MNF dummies; temperature distribution, tightness, and dummy product unloading efficiency under specified HTT conditions were obtained. The mock-up tests on the uranium nitride were carried out to prove the feasibility of MNF nitriding/denitriding processes, and the processes of the oxidation of MNF to U3O8, followed by the reduction to UO2. After the tests, the pulverized fuel was characterized for the particle size distribution, the bulk density, the angle of repose, and the phase composition by X-ray diffraction analysis. A material balance of uranium-containing product distributed over the units of the facility was drawn. The nitriding/denitriding processes proved ineffective to pulverize the MNF (25% of the loaded amount remained in claddings); nevertheless, X-ray diffraction showed a finely dispersed UN – U2N3 mixture in the powdered product. The nitride MNF oxidized in the Ar – 10% O2 gas mixture and the U3O8 reduced to UO2 in the Ar – 4% H2 atmosphere completely. According to the X-ray diffraction analysis, the produced UO2 did not contain a U3O8 phase and was a coarse powder, i.e. the fraction of particle size less than 100 µm was only 12.5%. The quantity of uranium in the product removed from the mock-up was 56% of the total amount used for the tests. The product loss was caused by the product deposits in the retort (13%) and a significant dust carryover to the off-gas from the retort during the tests (29%). The design of the scaled mock-up HTT facility requires improvements to reduce the internal deposits and the dust carryover from the facility together with off-gases.

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high-temperature treatment mixed uranium-plutonium nitride fuel BREST-OD-300 reactor SNF reprocessing module (RM) Experimental and Demonstration Energy Complex (EDEC)

Link for citing the article: Smirnov V.P., Samsonov A.A., Leshchenko A.Yu., Nosov A.V., Mochalov Yu.S., Savchits S.M., Legen’kij A.A. Development and Testing of a High-Temperature Treatment Facility Mock-Up for Pyroprocessing of Mixed Uranium-Plutonium Nitride SNF at Reprocessing Module of Experimental and Demonstration Energy Complex. Izvestiya vuzov. Yadernaya Energetika. 2026, no. 1, pp. 30-45; DOI: https://doi.org/10.26583/npe.2026.1.03 (in Russian).

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